1. Field of the Invention
This invention relates to an improved separable fasteners, particularly those of the hook and loop type, for attachment to other objects, particularly such objects as polyurethane foam seat cushions for automobiles, furniture and the like, wherein one portion of a separable fastener is incorporated into the foam object during the molding process for subsequent attachment to another object carrying the mating portion of the separable fastener. The improved fastener of the invention is easier to produce, store, transport, and use in the mold-in process and provides improved results both during and after the mold-in process.
2. Description of the Prior Art
Hook and loop type separable fasteners such as those sold by the assignee of this application under the trademark Velcro.RTM. are well-known and are used to join two members detachably to each other. This type of fastener has two components. Each has a flexible backing material having one component of the fastening system on the surface thereof. One surface is typically comprised of resilient hooks while the other is comprised of loops, and when the two surfaces are pressed together they interlock to form a releasable engagement.
Separable fasteners have in recent years been used in the manufacture of automobile seats in the attachment of the upholstered seat cover to the polyurethane foam bun. One portion of the separable fastener is incorporated onto the surface of the polyurethane foam bun during the foam molding process. The mating portion of the separable fastener is attached to the seat cover to provide releasable attachment to the foam bun. The separable fastener assembly used in the mold typically comprises the hooked portion of a separable fastener. It usually has a backing tape carrying resilient hooks, the backing tape being attached to a substrate. The outer surface of the substrate may carry projections to become incorporated into the foam to provide stable attachment of the separable fastener assembly to the foam article. In some assemblies, a magnetic shim is often placed between the backing tape and the substrate to facilitate placement in the trough of the mold cavity, which is equipped with magnets. A protective layer, usually in the form of a thin plastic film, may be placed over the resilient hooks to prevent incursion of foam into the hooks during the molding process, since significant contamination of the hooks would affect their ability to engage with the mating portion of the fastener attached to the seat cover. The assemblies are usually subjected to ultrasonic flattening at pre-determined lengths in order to mark the assembly for cutting, thus providing finished terminal ends.
One disadvantage of the separable fastener assemblies of the type disclosed in U.S. Pat. No. 4,673,542 is that the thin plastic film layer used to cover the hooks must be removed after the mold-in process, thus requiring an additional and somewhat painstaking step in the manufacture of the foam seat bun, and also requiring an additional component in the manufacture of the assembly which must be attached to the separable fastener tape with an adhesive. In addition, an adhesive-backed tape is usually affixed to the film layer to assist in its removal. Other prior-art assemblies, (including those disclosed in U.S. Pat. Nos. 4,726,975, 4,563,380 and 4,693,921) also employ a thin layer of film to prevent the incursion of foam into the projections of the separable fastener portion during mold-in. While French Patent 2,423,666 (Aplix) and U.S. Pat. No. 4,710,414 mention use of a foam to assist in sealing, the French patent never achieved commercial success and the U.S. Pat. No. ('414) still required use of a separable sealing film layer. The recently issued patent to Ogawa U.S. Pat. No. 4,842,916 (Jun. 27, 1989) disclosed the use of non-woven fabric or foam strips on the front edges of a fastener strip to seal against entry of a foaming liquid.
Other problems with the aforementioned prior art assemblies have been present. One disadvantage is that the most commonly used substrate materials, such as the loop-backed tapes, are relatively stiff, have a limited degree of flexibility, and have virtually no elasticity. Such assemblies have been shown to present problems of distortion after manufacture and during storage and shipment, resulting in a product which is wavy, curled, or stiffened ("beam" effect).